A precision temperature measuring explosion-proof shell for indium phosphide crystal growth and a temperature measuring method

Abstract

The application relates to the technical field of indium phosphide crystal growth, and particularly relates to a precise temperature measurement explosion-proof shell for indium phosphide crystal growth and a temperature measurement method. The explosion-proof shell body is in a cylindrical structure and is shaped to cover a quartz ampoule, and a carbon-carbon binding belt is sleeved on the outside of the explosion-proof shell body to cooperatively constrain radial expansion; the flexible graphite heat-conducting pad layer ensures that temperature measurement elements are in close contact with the outer wall of the ampoule with zero gap; and the double-sensing composite temperature measurement array realizes one-to-one pairing of discrete fixed-point and axial and circumferential full-range continuous temperature measurement. Through double-sensing real-time calibration and a multilayer thermal resistance coupling inversion algorithm, the application controls the real temperature precision of the melt within + / -0.3 DEG C, and in combination with a hierarchical thermal anomaly active explosion-proof interlocking system, three types of thermal anomaly working conditions are distinguished to perform differential responses, so that safety protection and precise temperature control are realized in the whole process of indium phosphide crystal growth.

Description

Technical Field

[0001] This invention belongs to the field of indium phosphide crystal growth technology, specifically relating to a precise temperature-measuring explosion-proof shell and temperature measurement method for indium phosphide crystal growth. Background Technology

[0002] In the production process of indium phosphide single crystals, both the Vertical Gradient Solidification (VGF) and Vertical Bridgman (VB) processes rely on quartz ampoules as sealed containers for crystal synthesis. The coupling effect of high-pressure phosphorus vapor and a high temperature of approximately 1100 degrees Celsius inside the ampoule subjectes the quartz tube wall to multiple effects of thermal stress, chemical corrosion, and mechanical loads over a long period. During the long crystal growth cycle, quartz ampoules frequently shatter due to microcrack propagation, wall thinning, or external mechanical impact. If an explosion fails, the splashing of high-temperature phosphorus media and broken quartz fragments can cause serious consequences such as furnace equipment damage, personnel burns, and crystal rod scrapping. Furthermore, it may trigger secondary explosions due to phosphorus vapor leakage. Given these safety risks, those skilled in the art have long been committed to building explosion-proof technology systems from multiple dimensions, including pressure control, atmosphere regulation, and structural reinforcement.

[0003] In terms of pressure control technology, existing patent documents disclose a variety of technical solutions. For example, patent CN202010713125.4 discloses a pressure control system and process for indium phosphide single crystal VGF process. It connects the single crystal furnace, vacuum pump, and compressed nitrogen cylinder using a five-way ball valve, and utilizes a two-stage pressure reducing valve to dynamically adjust the furnace pressure. Its core idea is to dynamically follow the phosphorus saturated vapor pressure inside the ampoule in the temperature-controlled zones, keeping the pressure difference within 1 atm during the isothermal stage and maintaining the furnace pressure consistently higher than the phosphorus pressure inside the tube during the cooling stage. A dual-sensor overpressure differential interlocking power reduction mechanism is used to prevent tube explosion from the source of pressure difference. Patent CN201721587953.8 discloses a nitrogen system for indium phosphide single crystal growth. The connection structure between the mechanical pump and the single crystal furnace ensures that the furnace vacuum reaches the process standard before nitrogen purging. It also employs an integrated design of multi-stage pressure reducing valves, buffer tanks, explosion-proof diaphragms, and one-way valves to achieve three nitrogen purgings to eliminate the influence of residual air.

[0004] Regarding ampoule structural reinforcement technology, patent CN201220493905.3 discloses a quartz explosion-proof container for single crystal growth, consisting of an inner crucible supporting the growth system and an outer thick-walled quartz pressure-bearing buffer structure. Fragments and phosphorus vapor from a damaged inner layer can be confined by the outer layer, thus preventing furnace deflagration. Patent CN201410669839.4 discloses a carbon plating method for quartz ampoules used for crystal growth. By decomposing acetylene at high temperature and depositing a carbon film on the inner wall of the ampoule, direct contact between phosphorus vapor, liquid indium, and SiO2 is effectively isolated, reducing wall corrosion thinning and pitting stress initiation points. Patent CN202210506066.2 further discloses a charging method for growing single crystals of indium phosphide polycrystalline material using the VGF or VB method. By setting up independent phosphorus source storage chambers and growth chambers, a physical separation structure is used to block the violent reaction between liquid indium backflow and red phosphorus, suppressing instantaneous overpressure and reducing tube wall phosphating.

[0005] Regarding temperature control and crystal growth process optimization, patent CN202410161454.0 discloses an indium phosphide crystal growth process. This process utilizes techniques such as slow heating at low temperatures to release water vapor and step-by-step heating and cooling to reduce the overall temperature difference of the ampoule, thus avoiding thermal shock and negative pressure differential-induced tube bursting. Patent CN201711428605.0 discloses a venting and sealing device and method for open-top quartz ampoules. This method eliminates thin spots and residual stress at the sealing point and removes cracked seals through graded high-vacuum evacuation and uniform sealing with a neutral oxyhydrogen flame.

[0006] However, with the continuous evolution of related technologies and the increasingly stringent requirements for crystal quality and production efficiency in high-end applications, some inherent characteristics of the existing technical solutions have gradually exposed deep-seated technical contradictions and limitations. First, in terms of pressure control, the existing solutions rely excessively on the long-term zero-point stability of high-precision pressure sensors and proportional valves. However, the growth cycle of VGF crystals is typically as long as 15 to 22 days. The high-temperature corrosive atmosphere will cause continuous oxidation and creep of the sensor's metal components, making zero-point drift unavoidable. The accuracy of differential pressure control will continue to deteriorate as the production cycle progresses, requiring shutdown for calibration approximately every two furnaces, severely reducing equipment uptime. In addition, PID regulation during high-flow charging and discharging processes is prone to overshoot and pressure oscillations. Instantaneous impact loads acting on the neck of the ampoule and the stress concentration area at the sealing point may induce new rupture risks. Secondly, regarding ampoule structural reinforcement, the double-layer irregular shape integral molding process is extremely difficult, with domestic quartz manufacturers achieving a mass production yield of less than 60%, significantly increasing scrap costs. The presence of interlayer air or vacuum layers hinders heat conduction, leading to a deterioration in furnace temperature field uniformity and a decrease in crystal solid-liquid interface stability. The irregular shape also presents challenges in cleaning and inspection, as well as non-reusability, further increasing consumable consumption rates. Thirdly, in terms of inner wall carbon coating protection, the additional vacuum coating process significantly extends the processing time of a single ampoule. Minor peeling of the carbon film during high-temperature, long-cycle processes may cause excessive carbon impurities in the InP crystal. Carbon films with difficulty in ensuring density are more prone to cracking and peeling under repeated high and low temperature cycles, making it difficult for the protective effect to last throughout the entire crystal growth cycle. Finally, in terms of temperature monitoring, existing solutions generally use thermocouples directly attached to the outer surface of the ampoule for single-point temperature measurement. This method has many inherent defects, such as discrete temperature measurement points that cannot construct a global temperature field, delayed response that cannot capture local instantaneous temperature rise changes, long-term high-temperature drift of thermocouple wires without a calibration mechanism, and simple sensing wiring that is prone to failure due to corrosion and thermal expansion and contraction. It not only fails to meet the process requirements of accurately controlling the temperature gradient of crystal growth, but also lacks the ability to issue early warnings at the budding stage of ampoule breakage risk.

[0007] In summary, while existing technologies offer various explosion-proof and temperature measurement solutions from the perspectives of pressure control, structural reinforcement, atmosphere regulation, and process optimization, these solutions either rely on high-cost equipment modifications and frequent calibration and maintenance, suffer from a rigid contradiction between process feasibility, yield rate, and consumable costs, fail to address the inherent brittleness of ampoule materials, or lack the monitoring capabilities for continuous temperature measurement across the entire range and early fault prediction. Therefore, how to simultaneously achieve high-precision, comprehensive temperature monitoring and proactive explosion-proof early warning while ensuring the safe and controllable growth process of indium phosphide crystals has become a key technical challenge for those skilled in the art, urgently requiring innovative technical solutions. Summary of the Invention

[0008] To overcome the problems in the prior art, the present invention provides a precise temperature-measuring explosion-proof shell and temperature measurement method for indium phosphide crystal growth.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution: a precision temperature-measuring explosion-proof shell for indium phosphide crystal growth, comprising an explosion-proof shell body made of carbon-carbon composite material, a flexible graphite thermally conductive pad layer disposed between the explosion-proof shell body and a quartz ampoule, and a dual-sensor composite temperature measurement array integrated in the explosion-proof shell body.

[0010] The explosion-proof outer shell is made of high-temperature resistant, high-strength carbon-carbon composite material, which is composed of carbon fiber braid and carbon matrix. Its overall structure is cylindrical, and the inner cavity contour is designed to match the outer surface of the quartz ampoule, completely covering the sidewalls, bottom, and top sealing area of ​​the quartz ampoule. The explosion-proof outer shell is divided into two independent petals. Each petal has multiple arrays of snap-fit ​​structures at its mating edges. Adjacent petals are interlocked through these snap-fit ​​structures to form a closed cylindrical protective structure. Each snap-fit ​​structure includes a protrusion on the edge of one petal and a groove on the edge of the other petal. The protrusion and groove are mechanically locked using an interference fit. At least two straps made of carbon-carbon composite material are also fitted to the outside of the explosion-proof outer shell. These straps are arranged circumferentially around the outer shell to help restrain radial expansion of the shell and prevent petal detachment under high-temperature conditions.

[0011] The flexible graphite thermal conductive pad is filled in the interlayer space between the explosion-proof outer shell and the quartz ampoule. The flexible graphite thermal conductive pad is made of compressible flexible graphite roll material and is laid along the entire gap between the outer wall of the quartz ampoule and the inner wall of the carbon-carbon outer shell. The function of the flexible graphite thermal conductive pad is to ensure a zero-gap fit between the temperature sensing element and the outer wall of the quartz ampoule, while providing an axial heat conduction channel so that the radiant heat from the heater can be evenly conducted to the sidewall of the quartz ampoule.

[0012] The dual-sensor composite temperature measurement array includes a platinum-rhodium thermocouple temperature measurement unit and a high-temperature resistant fiber optic grating temperature measurement unit.

[0013] The platinum-rhodium thermocouple temperature measurement unit uses PtRh30-PtRh6 type platinum-rhodium thermocouples, with no fewer than three, corresponding to the upper phosphorus source region, middle melt region, and lower seed crystal region inside the quartz ampoule, respectively. The temperature probes of each platinum-rhodium thermocouple are completely embedded within the flexible graphite thermally conductive pad layer, ensuring a seamless fit with the outer wall of the quartz ampoule. The leads of the platinum-rhodium thermocouples are protected by a high-temperature oxidation-resistant ceramic sheath, passing through the gap between the carbon-carbon outer shell and the furnace wall to the external data acquisition module.

[0014] The high-temperature resistant fiber Bragg grating temperature measurement unit employs a high-temperature resistant FBG fiber Bragg grating. The fiber Bragg grating is arranged axially through three temperature measurement zones along the carbon-carbon shell, and simultaneously wound at equal intervals circumferentially around the shell. The fiber Bragg grating is embedded within the carbon fiber braided layer of the carbon-carbon shell, forming an integrated structure with the carbon fiber braid. Each platinum-rhodium thermocouple has 2 to 3 sets of fiber Bragg grating measurement points corresponding to its axial direction, achieving a one-to-one pairing relationship between discrete fixed-point temperature measurement and continuous temperature measurement across the entire axial and circumferential domains.

[0015] A temperature measurement method based on the aforementioned precise temperature measurement explosion-proof enclosure includes the following steps: Step 1: Furnace assembly and sensor assembly. A segmented carbon-carbon composite shell is fitted over the outside of the quartz ampoule. The quartz ampoule is axially divided into three functional areas: an upper phosphorus source area, a middle melt area, and a lower seed crystal area. A flexible graphite thermally conductive pad is inserted between the carbon-carbon shell and the ampoule. The PtRh30-PtRh6 platinum-rhodium thermocouple is completely embedded in the pad, ensuring a seamless fit between the thermocouple probe and the outer wall of the quartz ampoule. A high-temperature resistant FBG fiber grating is wound axially through the three temperature measurement areas and circumferentially at equal intervals, pre-embedded in the shell's braided layer. This ensures that each thermocouple measurement point is matched with 2 to 3 fiber grating measurement points on both sides, completing the one-to-one pairing arrangement of thermocouples and fiber grating measurement points.

[0016] Step two: Power-on synchronization and zero-point calibration of the sensing system. After the crystal growth furnace is closed and sealed, the industrial control computer, thermocouple acquisition module, and fiber optic demodulator are simultaneously powered on and started. The acquisition module completes cold junction compensation baseline calibration for the thermocouples, and the fiber optic demodulator reads all initial reflection wavelengths of the FBG gratings to establish the basic conversion relationship between wavelength and temperature at room temperature. The industrial control computer has a built-in time synchronization chip, setting the synchronization time difference between the thermocouple and fiber optic grating signal acquisition to less than 1ms, achieving complete alignment of the time axes of the two temperature measurement data. After completing a full-channel self-test, removing abnormal sensing points with open wires or short circuits, and confirming that all dual-sensor arrays are functioning normally, the process proceeds.

[0017] Step 3: Simultaneous Acquisition and Real-time Calibration of Dual Sensors During Heating. The programmed heating process of the crystal growth furnace is initiated, with continuous synchronous acquisition of dual-sensor data throughout the heating process. One sensor acquires the steady-state temperature of thermocouples at fixed points in each zone, while the other sensor uses a fiber optic demodulator to acquire the reflected wavelengths of all FBG gratings and converts them to obtain continuous temperature field distribution data of the carbon-carbon shell in the axial and circumferential directions. The industrial control system extracts the temperature values ​​of paired thermocouples and fiber optic gratings at the same location every 5 minutes. Using the temperature measured by a high-precision platinum-rhodium thermocouple as the true reference, the wavelength and temperature conversion coefficients of the corresponding fiber optic gratings are automatically iteratively corrected to compensate for the creep effect of the fiber under high-temperature conditions and the temperature drift caused by coating aging. A piecewise nonlinear interpolation algorithm is used, combined with the true values ​​of the thermocouples at fixed points and the continuous temperature measurement curves of the fiber optics, to reconstruct the complete two-dimensional temperature distribution data of the quartz ampoule's outer wall.

[0018] Step four: Layered thermal resistance coupling inversion calculation of the true melt temperature. The reconstructed two-dimensional temperature field data of the ampoule's outer wall is input into the multilayer thermal conduction model built into the industrial control system. The contact thermal resistance and radiative heat transfer loss of each layer—the carbon-carbon outer shell, the flexible graphite thermal pad, the quartz tube wall, and the barrier coating—are calculated layer by layer to correct for temperature deviations caused by minute temperature measurement gaps resulting from thermal expansion mismatch in the multilayer materials. This model calculates and outputs the true melt temperature in real time at three locations inside the ampoule: the phosphorus source vaporization zone, the InP melt center, and the solid-liquid growth interface, ensuring stable temperature control accuracy within ±0.3 degrees Celsius.

[0019] Step 5: The industrial control system continuously compares the synchronous temperature change rates of thermocouples and fiber Bragg gratings in the same area, distinguishes three types of thermal anomalies, and performs graded handling. When a uniform and slow temperature shift is detected across the entire area, it is determined to be fiber Bragg grating sensor aging, and the system automatically starts the global parameter compensation program without interrupting the crystal growth process. When a short-term temperature jump is detected at a local grating measuring point and the paired thermocouples heat up synchronously, it is determined to be due to the shedding of the interlayer graphite pad, microcracks in the ampoule PBN coating, or trace infiltration of phosphorus vapor. The system outputs a first-level audible and visual explosion-proof warning and simultaneously reduces the heating power of the corresponding area. When a rapid increase in the axial temperature difference of a single temperature measuring interval is detected in a short period of time, it is determined to be due to the failure of the carbon-carbon shell elastic support or the ampoule eccentric tilting. The system triggers the second-level explosion-proof interlock protection, performs segmented slow cooling and nitrogen purging and pressure stabilization operations in the furnace cavity, and avoids the risk of high-temperature explosion of the ampoule from the source.

[0020] Step Six: Closed-Loop Temperature Control During the Isothermal Synthesis Stage. During the isothermal synthesis of indium phosphide polycrystalline silicon, the temperature measurement, calibration, temperature inversion, and anomaly identification processes from Steps Three to Five are continuously repeated. The corrected actual melt temperature and the global shell temperature field data are synchronously transmitted to the in-situ crystal quality detection module. The heating power of the multi-zone single-crystal furnace is adjusted to dynamically optimize the axial temperature gradient and suppress the formation of crystal defects such as impurities, compositional segregation, and porosity.

[0021] Step 7: Data storage and archiving of temperature measurements throughout the cooling phase. After crystal synthesis, the furnace enters a gradient cooling process. The dual-sensor system continuously and synchronously acquires, calibrates, and inverts temperature data until the furnace reaches room temperature. The industrial control system fully stores the raw thermocouple data, continuous temperature field curves of the fiber optic grating, calibration correction parameters, and thermal anomaly warning records for the entire furnace heating, isothermal, and cooling process. This stored data is used for post-furnace analysis of thermal field uniformity, assessment of carbon shell wear, and provides a quantitative basis for the segmented replacement of the carbon shell.

[0022] Step 8: Re-inspection and calibration of the sensing components after furnace exit. Open the furnace and remove the carbon-carbon outer shell to check the integrity of the thermocouple and FBG fiber grating coating. Perform standard temperature range re-inspection and calibration of the sensing components, update the basic conversion parameters of the grating, and undamaged components can be directly reused in the next synthesis process.

[0023] Furthermore, in a preferred embodiment, the explosion-proof outer shell is divided into two independent upper and lower lobes. Multiple sets of array-type snap-fit ​​structures are respectively provided at the mating edges of the upper and lower lobes. During assembly, the lower lobe is first fixedly placed in the heating zone of the crystal growth furnace. Then, a quartz ampoule filled with raw materials is dropped into the lower lobe of the carbon-carbon outer shell and flame-sealed. Finally, the upper lobe is closed and the corresponding snap-fits are engaged to form a closed cylindrical protective structure. After the snap-fits are engaged, two carbon-carbon straps of identical specifications and material are used to wrap around the top and bottom of the shell for reinforcement. Multiple limiting structures work together to constrain the radial expansion of the shell and the loosening of the lobes under high-temperature conditions. A small observation opening is provided on the side wall of the upper lobe. This window faces the furnace camera monitoring optical path, ensuring unobstructed observation of the indium phosphide melt surface state inside the crucible and the entire crystal growth process by the industrial camera, achieving real-time visual monitoring of the growth status.

[0024] Furthermore, in another preferred embodiment, the carbon-carbon composite material can be replaced with graphite, stainless steel, silicon carbide composite material, or silicon carbide fiber-reinforced silicon carbide composite material. When graphite is used, the graphite shell is entirely made of high-purity graphite blocks, and the inner cavity contour matches the outer surface of the quartz ampoule. The graphite shell is divided into two or more independent petals along the dividing line, and the petals are mechanically connected and sealed by graphite connectors. When stainless steel is used, the stainless steel shell is welded from high-temperature resistant austenitic stainless steel plates, with a wall thickness that meets pressure resistance requirements, and the inner cavity also adopts a contour-matching design. When silicon carbide composite material is used, the silicon carbide shell is made of silicon carbide fiber-reinforced silicon carbide matrix, which has excellent high-temperature resistance and oxidation resistance.

[0025] Furthermore, the specific implementation methods of the primary warning and secondary interlock protection of the graded thermal anomaly active explosion-proof interlock system are as follows: In the primary warning state, the system outputs an audible and visual alarm signal to the central control interface, and simultaneously sends a power reduction command to the heating power controller to reduce the heating power of the corresponding temperature zone once, and extends the temperature sampling interval of that area to continuously monitor the abnormal evolution trend. In the secondary interlock protection state, the system immediately sends a full-power stop command to the heating power controller, and simultaneously sends a nitrogen charging command to the nitrogen charging system to increase the furnace cavity pressure, establish a positive pressure difference to suppress the ampoule rupture process, and then executes a segmented slow cooling program to reduce the temperature of each temperature zone, stabilizes the pressure for 2 hours, and then continues to slowly cool down to room temperature.

[0026] Furthermore, the observation aperture of the carbon-carbon outer shell adopts a quartz glass sealed window structure. The opening size of the observation aperture is determined according to the observation field requirements of the industrial camera. The quartz glass sealed window and the carbon-carbon outer shell are sealed by high-temperature sealant bonding or mechanical compression to ensure that the observation aperture maintains airtightness under the high temperature and high pressure environment inside the furnace.

[0027] Furthermore, the carbon fiber braid of the carbon-carbon outer shell adopts a three-dimensional braided structure or an orthogonal braided structure to provide sufficient interlaminar shear strength and impact resistance. The carbon matrix is ​​densified by chemical vapor deposition or liquid phase impregnation carbonization to ensure the structural stability and oxidation resistance of the carbon-carbon composite material under long-term working conditions.

[0028] Furthermore, the cold junction compensation of the platinum-rhodium thermocouple is achieved using a specially designed cold junction compensation module. This module is located outside the furnace in a temperature-stable region, and a precision platinum resistance thermometer monitors the temperature at the compensation point and corrects the thermocouple measurements in real time. Wavelength demodulation of the fiber optic grating is achieved using a high-speed demodulator to ensure rapid response to sudden temperature changes.

[0029] Furthermore, the crystal growth process based on the aforementioned precise temperature-measuring explosion-proof shell also includes an in-situ quality detection linkage function. The in-situ quality detection module receives melt temperature field data and global shell temperature field data from a dual-sensor system. By comparing the temperature gradient near the solid-liquid interface with the theoretically optimal temperature gradient, it assesses the interface stability of crystal growth in real time. When a temperature gradient deviates from a set threshold, the in-situ quality detection module automatically generates a power adjustment suggestion and sends it to the heating power controller for execution, achieving closed-loop optimization control of crystal growth.

[0030] Furthermore, the service life assessment method for the carbon-carbon shell body is as follows: Based on stored full-process temperature data and thermal anomaly warning records, the system calculates the number of temperature cycles, maximum operating temperature, and cumulative thermal stress load of the carbon-carbon shell during historical production cycles. By comparing this with a preset carbon-carbon material fatigue life curve, the remaining service life of the carbon-carbon shell is predicted and a reminder is displayed on the interface. When the carbon-carbon shell reaches the preset replacement cycle or structural damage characteristics are detected, the system automatically generates a replacement reminder work order to guide maintenance personnel to replace it in a timely manner.

[0031] The beneficial effects of this invention are: First, this invention forms a fully flexible, buffered, and explosion-proof constraint layer by encasing the quartz ampoule in a carbon-carbon composite explosion-proof shell. The carbon-carbon composite material possesses excellent high-temperature resistance and mechanical strength, which can restrain the high-temperature medium and broken quartz fragments from splashing outwards when the ampoule breaks, protecting the single-crystal furnace equipment and operators. Simultaneously, the carbon-carbon shell isolates the ampoule from direct contact with the hard components of the furnace chamber, absorbing thermal stress and buffering impacts, thus physically reducing the probability of ampoule breakage. Combined with the early damage prediction capability of the full-range temperature field provided by the dual-sensor system, this invention achieves a dual explosion-proof mechanism of "early warning + physical buffering," significantly reducing the frequency of furnace cleaning shutdowns and improving equipment uptime.

[0032] Secondly, this invention achieves full-coverage monitoring of the temperature field on the outer wall of the ampoule through a dual-sensor composite temperature array. The continuous arrangement of FBG fiber gratings along the axial and circumferential directions of the shell compensates for the shortcomings of discrete monitoring by single-point thermocouples, eliminating temperature measurement blind spots. The one-to-one pairing of fiber grating measurement points with platinum-rhodium thermocouple measurement points ensures that each region possesses a high-precision reference temperature and continuous temperature change trend monitoring capability. The dual-sensor real-time calibration mechanism effectively offsets the temperature drift caused by the fiber under long-term high-temperature conditions. After correction using a multi-layer thermal resistance model, the melt temperature measurement error is controlled within ±0.3 degrees Celsius, significantly improving temperature control accuracy and providing a reliable data foundation for precise and stable control of the indium phosphide crystal growth temperature gradient.

[0033] Third, the graded thermal anomaly active explosion-proof interlocking system of the present invention can accurately distinguish three different types of thermal anomaly conditions and execute targeted graded responses. Unlike existing technologies that only set a fixed over-temperature threshold for a single interlocking logic, the system of the present invention can identify different characteristics such as uniform drift caused by sensor aging, temperature spikes caused by localized damage, and drastic changes in axial temperature difference caused by structural failure, and execute differentiated response strategies such as parameter compensation, first-level early warning, and second-level interlocking respectively. This graded response method effectively avoids unnecessary shutdowns caused by misjudgments due to sensor aging, ensuring the continuity and stability of the crystal growth process. Simultaneously, it can promptly trigger explosion-proof actions when a real structural failure risk occurs, preventing the accident from escalating.

[0034] Fourth, the carbon-carbon shell of this invention features a detachable design, allowing the thermocouples and fiber optic grating sensing components to be inspected, calibrated, and reused after each batch of production, significantly reducing the cost of sensing elements. The carbon-carbon shell itself employs a segmented, petal-like structure design; in the event of localized damage, only the damaged segment needs replacement, eliminating the need for complete replacement and further reducing consumable costs. Through the accompanying full-process temperature data storage, archiving, and wear assessment functions, the system can quantitatively evaluate the wear status of the carbon-carbon shell and quartz ampoules, predict consumable failure cycles, achieve preventative maintenance, and avoid sudden safety accidents and production interruptions.

[0035] Fifth, the precision temperature-measuring explosion-proof shell of this invention achieves uniform heat transfer from the heater to the quartz ampoule through a flexible graphite thermally conductive pad layer. This significantly reduces the temperature difference in the circumferential and vertical directions of the ampoule, resulting in more uniform heating of the indium phosphide melt. It also reduces drastic changes in fluid convection caused by localized overcooling or overheating, thereby lowering the probability of dislocation defects. The carbon-carbon composite material possesses both high thermal conductivity and moderate insulation properties. The efficient heat transfer to the quartz on the inner side and the low thermal conductivity on the outer side, which prevents heat loss through radiation, reduce the temperature difference within the furnace and stabilize the longitudinal temperature gradient. This is beneficial for achieving stable constant-diameter growth and increasing the drawing speed.

[0036] Sixth, the small observation aperture design of the carbon-carbon shell in this invention allows the industrial camera to observe the state of the indium phosphide melt inside the crucible and the entire crystal growth process without obstruction, realizing real-time visual monitoring of the growth state. This design overcomes the shortcomings of existing technologies where the carbon film coating causes tube wall devitrification and makes direct observation impossible, providing direct visual feedback for process debugging and control.

[0037] In summary, the precision temperature-measuring explosion-proof shell for indium phosphide crystal growth provided by this invention achieves safety protection and precise temperature control throughout the entire indium phosphide crystal growth process through physical explosion-proof protection of carbon-carbon composite materials, full-range temperature monitoring of a dual-sensor composite temperature measurement array, high-precision temperature calculation using dual-sensor calibration and a multi-layer thermal resistance temperature inversion algorithm, and intelligent graded response of a graded thermal anomaly active explosion-proof interlocking system. This effectively solves the technical defects of existing technologies, such as the lack of explosion-proof protection for ampoules, insufficient accuracy of single-point temperature measurement, and lack of early fault warning. While improving the safety of crystal growth, it also significantly improves crystal quality, reduces production costs, and increases production efficiency. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0039] Figure 2 This is a cross-sectional view of the present invention.

[0040] Figure 3 This is a detailed structural diagram of the snap-fit ​​structure in this invention.

[0041] Figure 4 This is a flowchart of the temperature measurement method of the present invention.

[0042] In the attached diagram, the following are the reference numerals: 1. Explosion-proof housing body; 2. Flexible graphite thermal conductive pad layer; 3. Dual-sensor composite temperature measurement array; 4. Platinum-rhodium thermocouple temperature measurement unit; 5. High-temperature resistant fiber optic grating temperature measurement unit; 6. Quartz ampoule; 7. Snap-fit ​​structure; 7a. Protruding tongue; 7b. Groove; 8. Carbon fiber strapping; 9. Upper lobe; 10. Lower lobe. Detailed Implementation

[0043] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to facilitate understanding by those skilled in the art.

[0044] The precision temperature-measuring explosion-proof housing for indium phosphide crystal growth of the present invention has the following overall assembly structure: Figure 1As shown, the device mainly consists of an explosion-proof housing 1 made of carbon-carbon composite material, a flexible graphite thermally conductive pad 2 disposed between the explosion-proof housing 1 and the quartz ampoule 6, and a dual-sensor composite temperature measurement array 3 integrated into the explosion-proof housing 1. These components work collaboratively during the growth of indium phosphide single crystals using the vertical gradient solidification method or the vertical Bridgman method to achieve physical explosion-proof protection and high-precision global temperature monitoring of the sealed quartz ampoule 6.

[0045] In practical implementation, the explosion-proof housing body 1 is made of high-temperature resistant, high-strength carbon-carbon composite material, which is composed of a carbon fiber braid and a carbon matrix. The carbon fiber braid adopts a three-dimensional braided structure or an orthogonal braided structure to provide sufficient interlaminar shear strength and impact resistance. The carbon matrix is ​​densified by chemical vapor deposition or liquid phase impregnation carbonization to ensure the structural stability and oxidation resistance of the carbon-carbon composite material under long-term working conditions. The explosion-proof housing body 1 has an overall cylindrical structure, and its inner cavity contour is designed to match the outer surface of the quartz ampoule 6, which can completely cover the side walls, bottom, and top sealing area of ​​the quartz ampoule 6.

[0046] The explosion-proof enclosure body 1 is divided into two independent lobes along the transverse or longitudinal direction. Multiple array-type snap-fit ​​structures 7 are provided at the mating edges of each lobe. Adjacent lobes are interlocked through the snap-fit ​​structures 7 to form a closed cylindrical protective structure. The snap-fit ​​structure 7 includes a protruding tongue 7a located on the edge of one lobe and a groove 7b located on the edge of the other lobe. The protruding tongue 7a and the groove 7b are mechanically locked using an interference fit. At least two straps 8 made of carbon-carbon composite material are fitted around the outside of the explosion-proof enclosure body 1. The straps 8 are arranged around the circumference of the enclosure to help restrain the radial expansion of the enclosure and the loosening of the lobes under high-temperature conditions.

[0047] A flexible graphite thermal conductive pad 2 is filled in the space between the explosion-proof housing 1 and the quartz ampoule 6. The flexible graphite thermal conductive pad 2 is made of compressible flexible graphite roll material and is laid along the entire gap between the outer wall of the quartz ampoule 6 and the inner wall of the carbon-carbon housing. The function of the flexible graphite thermal conductive pad 2 is to ensure that the temperature sensing element and the outer wall of the quartz ampoule 6 achieve zero-gap contact, while providing an axial heat conduction channel so that the radiant heat from the heater can be evenly conducted to the side wall of the quartz ampoule 6.

[0048] The dual-sensor composite temperature measurement array 3 includes a platinum-rhodium thermocouple temperature measurement unit 4 and a high-temperature resistant fiber optic grating temperature measurement unit 5. The platinum-rhodium thermocouple temperature measurement unit 4 uses PtRh30-PtRh6 type platinum-rhodium thermocouples, with at least three units, corresponding to the upper phosphorus source region, middle melt region, and lower seed crystal region inside the quartz ampoule 6, respectively. The temperature probes of each platinum-rhodium thermocouple are completely embedded inside the flexible graphite thermally conductive pad layer 2, ensuring a seamless fit with the outer wall of the quartz ampoule 6. The leads of the platinum-rhodium thermocouples are protected by a high-temperature oxidation-resistant ceramic sheath, passing through the gap between the carbon shell and the furnace wall to the external data acquisition module.

[0049] The high-temperature resistant fiber grating temperature measurement unit 5 employs a high-temperature resistant FBG fiber grating. The fiber grating is arranged along the axial direction of the carbon-carbon shell, penetrating three temperature measurement areas, and simultaneously wound at equal intervals along the circumference of the shell. The fiber grating is embedded within the carbon fiber braided layer of the carbon-carbon shell, forming an integrated structure with the carbon fiber braid. Each platinum-rhodium thermocouple measurement point has 2 to 3 sets of fiber grating measurement points corresponding to its axial direction, achieving a one-to-one pairing relationship between discrete fixed-point temperature measurement and continuous temperature measurement across the entire axial and circumferential domains.

[0050] Figure 1 , Figure 3 As shown, the explosion-proof housing 1 is divided into an upper lobe 9 and a lower lobe 10. The lower lobe 10 is fixedly placed in the heating zone of the crystal growth furnace. After the quartz ampoule 6 containing the raw materials is dropped into the lower lobe of the carbon-carbon housing and the flame-sealing operation is completed, the upper lobe 9 is closed and the corresponding buckles are fastened to form a closed cylindrical protective structure. After the buckles are locked, two carbon-carbon straps 8 of the same specifications and material are used to wrap around the top and bottom of the housing for reinforcement. A small observation opening is provided on the side wall of the upper lobe 9. This window faces the camera monitoring optical path of the furnace, ensuring that the industrial camera can observe the state of the indium phosphide melt inside the crucible and the entire crystal growth process without obstruction. The observation opening adopts a quartz glass sealed window structure, and the opening size is determined according to the observation field requirements of the industrial camera.

[0051] Figure 2 This is a cross-sectional view of the invention, showing the internal structure of the explosion-proof housing 1, the arrangement of the platinum-rhodium thermocouples and fiber optic gratings in the three axial temperature measurement areas of the dual-sensor composite temperature measurement array 3, and the state of the flexible graphite thermal conductive pad 2 filled between the housing and the ampoule. From Figure 3 As can be clearly seen, the platinum-rhodium thermocouple probe is completely embedded inside the flexible graphite thermal pad layer 2, maintaining a seamless fit with the outer wall of the quartz ampoule 6. A fiber optic grating forms a continuous temperature measurement network along the axial and circumferential directions of the carbon-carbon shell.

[0052] Figure 3The diagram shows a detailed view of the snap-fit ​​structure 7. Multiple arrays of snap-fit ​​structures 7, arranged at the mating edges of adjacent valve bodies, include an interference fit connection between a tongue 7a and a groove 7b. The tongue 7a is located at the edge of one valve body, and the groove 7b is located at the edge of the other valve body; the two are mechanically locked together using an interference fit. Carbon fiber strapping 8 is arranged circumferentially around the shell, working together to restrain the radial expansion of the shell and prevent valve detachment under high-temperature conditions.

[0053] In a preferred embodiment of the present invention, the explosion-proof shell body 1 is divided into two independent upper and lower lobes. Multiple array-type snap-fit ​​structures 7 are respectively provided on the mating edges of the upper lobe 9 and the lower lobe 10. During assembly, the lower lobe 10 is first fixedly placed in the heating zone of the crystal growth furnace. Then, quartz ampoules 6 filled with raw materials are dropped into the lower lobe of the carbon-carbon shell and flame-sealed. Finally, the upper lobe 9 is closed and the corresponding snap-fits are engaged to form a closed cylindrical protective structure. After the snap-fits are engaged, two carbon-carbon straps 8 of identical specifications and material are used to wrap around the top and bottom of the shell for reinforcement. Multiple limiting structures work together to constrain the radial expansion of the shell and the loosening of the lobes under high-temperature conditions. The small observation port on the side wall of the upper lobe 9 faces the furnace camera monitoring optical path, ensuring unobstructed observation of the indium phosphide melt surface state inside the crucible and the entire crystal growth process by the industrial camera, achieving real-time visual monitoring of the growth status.

[0054] Furthermore, cold junction compensation for the platinum-rhodium thermocouple is achieved using a specially designed cold junction compensation module. This module is located outside the furnace in a temperature-stable region, and a precision platinum resistance thermometer monitors the temperature at the compensation point and corrects the thermocouple measurements in real time. Wavelength demodulation of the fiber optic grating is achieved using a high-speed demodulator with a sampling frequency of at least 100Hz to ensure rapid response to sudden temperature changes.

[0055] The temperature measurement method for the precise temperature measurement explosion-proof enclosure based on the present invention, such as Figure 4 As shown, the specific implementation steps are as follows.

[0056] Step one involves assembling the sensing components for the furnace. A segmented carbon-carbon composite shell is fitted over the outside of the quartz ampoule 6. The interior of the quartz ampoule 6 is divided axially into three functional areas: an upper phosphorus source area, a middle melt area, and a lower seed crystal area. A flexible graphite thermally conductive pad 2 is inserted between the carbon-carbon shell and the ampoule. The PtRh30-PtRh6 platinum-rhodium thermocouple is completely embedded within the pad, ensuring a seamless fit between the thermocouple probe and the outer wall of the quartz ampoule 6. A high-temperature resistant FBG fiber grating is wound axially through the three temperature measurement areas and circumferentially at equal intervals within the shell's braided layer. This ensures that each thermocouple measurement point is matched with 2 to 3 fiber grating measurement points on both sides, completing the one-to-one pairing arrangement of thermocouples and fiber grating measurement points.

[0057] Step two involves powering on and synchronizing the zero-point calibration of the sensing system. After the crystal growth furnace is sealed, the industrial control computer, thermocouple acquisition module, and fiber optic demodulator are simultaneously powered on and started. The acquisition module performs cold junction compensation baseline calibration on the thermocouples, and the fiber optic demodulator reads the initial reflection wavelengths of all FBG gratings, establishing a basic conversion relationship between wavelength and temperature at room temperature. The industrial control computer has a built-in time synchronization chip, setting the synchronization time difference between the thermocouple and fiber optic grating signal acquisition to less than 1ms, ensuring complete alignment of the time axes of the two temperature measurement data. After completing a full-channel self-test, removing faulty sensing points with open circuits or short circuits, and confirming that all dual-sensor arrays are functioning correctly, the process proceeds.

[0058] Step three involves simultaneous acquisition and real-time calibration of dual sensors during the heating phase. The programmed heating process of the crystal growth furnace is initiated, with continuous synchronous acquisition of dual-sensor data throughout the heating process. One sensor acquires the steady-state temperature of thermocouples at fixed points in each zone, while the other sensor uses a fiber optic demodulator to acquire the reflected wavelengths of all FBG gratings and converts them to obtain continuous temperature field distribution data of the carbon-carbon shell in the axial and circumferential directions. The industrial control system extracts the temperature values ​​of paired thermocouples and fiber optic gratings at the same location every 5 minutes. Using the temperature measured by a high-precision platinum-rhodium thermocouple as the true reference, the wavelength and temperature conversion coefficients of the corresponding fiber optic gratings are automatically iteratively corrected to compensate for the creep effect of the fiber under high-temperature conditions and the temperature drift caused by coating aging. A piecewise nonlinear interpolation algorithm is used, combined with the true values ​​of the thermocouples at fixed points and the continuous temperature measurement curves of the fiber optics, to reconstruct the complete two-dimensional temperature distribution data of the outer wall of the quartz ampoule 6.

[0059] Step four involves layered thermal resistance coupling inversion calculation of the true melt temperature. The reconstructed two-dimensional temperature field data of the ampoule's outer wall is input into the multilayer thermal conduction model built into the industrial control system. The contact thermal resistance and radiative heat transfer loss of each layer—the carbon-carbon outer shell, the flexible graphite thermal pad layer 2, the quartz tube wall, and the barrier coating—are calculated layer by layer to correct for temperature deviations caused by minute temperature measurement gaps resulting from thermal expansion mismatch in the multilayer materials. This model calculates and outputs the true melt temperature in real time at three locations inside the ampoule: the phosphorus source vaporization zone, the InP melt center, and the solid-liquid growth interface, ensuring stable temperature control within ±0.3 degrees Celsius.

[0060] Step five involves the industrial control system continuously comparing the synchronous temperature change rates of thermocouples and fiber Bragg gratings in the same area, distinguishing three types of thermal anomalies, and implementing graded handling. When a uniform and slow temperature shift is detected across the entire area, it is determined to be fiber Bragg grating sensor aging, and the system automatically initiates a global parameter compensation program without interrupting the crystal growth process. When a short-term temperature jump is detected at a local grating measuring point and the paired thermocouples heat up synchronously, it is determined to be due to the shedding of the interlayer graphite pad, microcracks in the ampoule PBN coating, or trace infiltration of phosphorus vapor. The system outputs a first-level audible and visual explosion-proof warning and simultaneously reduces the heating power of the corresponding area. When a rapid increase in the axial temperature difference within a single temperature measuring range is detected in a short period, it is determined to be due to the failure of the carbon-carbon shell elastic support or the ampoule's eccentric tilt. The system triggers a second-level explosion-proof interlock protection, performing segmented slow cooling and nitrogen purging and pressure stabilization operations in the furnace cavity to avoid the risk of ampoule high-temperature explosion from the source.

[0061] Step six involves closed-loop temperature control during the isothermal synthesis stage. During the isothermal synthesis of indium phosphide polycrystalline silicon, the temperature measurement, calibration, temperature inversion, and anomaly identification processes from steps three to five are continuously repeated. The corrected melt temperature and the global shell temperature field data are synchronously transmitted to the in-situ crystal quality detection module. This adjusts the multi-zone heating power of the single-crystal furnace, dynamically optimizes the axial temperature gradient, and suppresses the formation of crystal defects such as impurities, compositional segregation, and porosity.

[0062] Step seven involves storing and archiving the temperature data from the entire cooling process. After crystal synthesis, the furnace enters a gradient cooling phase. The dual-sensor system continuously and synchronously acquires, calibrates, and inverts temperature data until the furnace reaches room temperature. The industrial control system comprehensively stores the raw thermocouple data, continuous temperature field curves of the fiber optic grating, calibration and correction parameters, and thermal anomaly warning records for the entire furnace heating, isothermal, and cooling process. This stored data is used for post-furnace analysis of thermal field uniformity, assessment of carbon shell wear, and provides a quantitative basis for the segmented replacement of the carbon shell.

[0063] Step eight involves re-inspecting and calibrating the sensing components after the furnace is removed. The furnace is opened, the carbon-carbon outer shell is removed, and the integrity of the thermocouples and FBG fiber grating coating is checked. The sensing components are re-calibrated within the standard temperature range, and the basic conversion parameters of the grating are updated. Components without damage can be directly reused in the next synthesis process.

[0064] Furthermore, the multi-layer heat conduction model built into the industrial control system includes the following parameter layers: the carbon-carbon outer shell layer uses an anisotropic thermal conductivity tensor to describe its axial and radial thermal conductivity differences; the flexible graphite thermal pad layer 2 uses an equivalent thermal conductivity to describe its axial thermal conduction performance under compression; the quartz tube wall uses an isotropic thermal conductivity; and the barrier coating uses the actually measured thermal conductivity and thickness. The contact thermal resistance between each layer is determined using empirical formulas or measured data, and the radiative heat transfer loss is calculated using the Stefan-Boltzmann law. The model input is the measured data of the two-dimensional temperature field of the ampoule's outer wall, and the model output is the actual melt temperature at three characteristic locations inside the ampoule.

[0065] Furthermore, the specific implementation methods of the primary warning and secondary interlock protection of the graded thermal anomaly active explosion-proof interlock system are as follows: In the primary warning state, the system outputs an audible and visual alarm signal to the central control interface, and simultaneously sends a power reduction command to the heating power controller to reduce the heating power of the corresponding temperature zone once, and extends the temperature sampling interval of that area to continuously monitor the abnormal evolution trend. In the secondary interlock protection state, the system immediately sends a full-power stop command to the heating power controller, and simultaneously sends a nitrogen charging command to the nitrogen charging system to increase the furnace chamber pressure, establish a positive pressure difference to suppress the ampoule rupture process, and then executes a segmented slow cooling program to reduce the temperature of each temperature zone. After maintaining the pressure for 2 hours, it continues to slowly cool down to room temperature.

[0066] Furthermore, the crystal growth process based on a precision temperature-measuring explosion-proof shell also includes an in-situ quality inspection linkage function. The in-situ quality inspection module receives melt temperature field data and global shell temperature field data from a dual-sensor system. By comparing the temperature gradient near the solid-liquid interface with the theoretically optimal temperature gradient, it evaluates the interface stability of crystal growth in real time. When a temperature gradient deviates from a set threshold, the in-situ quality inspection module automatically generates a power adjustment suggestion and sends it to the heating power controller for execution, achieving closed-loop optimization control of crystal growth.

[0067] Furthermore, the lifespan assessment method for the carbon-carbon shell body is as follows: Based on the stored full-process temperature data and thermal anomaly warning records, the system calculates the number of temperature cycles, the highest operating temperature, and the cumulative thermal stress load of the carbon-carbon shell during historical production cycles. By comparing this with the preset carbon-carbon material fatigue life curve, the remaining lifespan of the carbon-carbon shell is predicted and a reminder is displayed on the interface. When the carbon-carbon shell reaches the preset replacement cycle or structural damage characteristics are detected, the system automatically generates a replacement reminder work order to guide maintenance personnel to replace it in a timely manner.

[0068] In another preferred embodiment, the carbon-carbon composite material can be replaced with graphite, stainless steel, silicon carbide composite material, or silicon carbide fiber-reinforced silicon carbide composite material. When graphite is used, the entire graphite shell is made of high-purity graphite blocks, and the inner cavity contour matches the outer surface of the quartz ampoule 6. The graphite shell is divided into two or more independent petals along the dividing line, and the petals are mechanically connected and sealed by graphite connectors. When stainless steel is used, the stainless steel shell is welded from high-temperature resistant austenitic stainless steel sheets, with a wall thickness that meets pressure resistance requirements. The inner cavity also adopts a contour-matching design. When silicon carbide composite material is used, the silicon carbide shell is made of silicon carbide fiber-reinforced silicon carbide matrix, which has excellent high-temperature resistance and oxidation resistance.

[0069] To verify the technical effects of the present invention, specific embodiments are provided below. Example

[0070] This embodiment uses the precision temperature-measuring explosion-proof housing of the present invention to conduct an indium phosphide crystal growth experiment. The explosion-proof housing body is made of carbon-carbon composite material and is divided into two independent lobes, an upper lobe and a lower lobe, along the transverse direction. A flexible graphite thermally conductive pad is disposed between the explosion-proof housing body and the quartz ampoule. The dual-sensor composite temperature measurement array includes three PtRh30-PtRh6 type platinum-rhodium thermocouples and a high-temperature resistant FBG fiber grating network arranged along the axial direction.

[0071] During crystal growth, the temperature measurement method of this invention is used for full-process temperature monitoring. During the heating phase, the dual-sensor synchronous acquisition frequency is 100Hz, with a calibration iteration completed every 5 minutes. A multilayer heat conduction model calculates the actual melt temperature in real time, with temperature control accuracy stable within ±0.25 degrees Celsius.

[0072] After crystal growth was completed, the crystal quality was tested. The results showed that the indium phosphide single crystal grown using the apparatus and method of this invention had a dislocation density reduced to below 800 dislocations per square centimeter, and the crystal integrity was significantly improved. Simultaneously, no ampoule breakage occurred during the entire crystal growth cycle. The dual-sensor system successfully identified and issued warnings for two minor local graphite pad detachment events, and the system automatically executed a level-one warning response, effectively preventing the incidents from escalating.

[0073] Furthermore, the small viewing aperture design of the carbon-carbon shell in this invention allows the industrial camera to observe the state of the indium phosphide melt surface and the entire crystal growth process inside the crucible without obstruction, achieving real-time visual monitoring of the growth state. This design overcomes the shortcomings of existing technologies where the carbon film coating causes tube wall devitrification, making direct observation impossible, and provides direct visual feedback for process debugging and control.

[0074] In practice, the quartz glass sealing window of the observation aperture is sealed to the carbon-carbon outer shell using high-temperature sealant or mechanical compression to ensure airtightness of the observation aperture under the high temperature and pressure environment inside the furnace. The opening size is determined according to the observation field requirements of the industrial camera, ensuring complete coverage of the indium phosphide molten surface area inside the crucible.

[0075] The precision temperature-measuring explosion-proof shell of this invention achieves uniform heat transfer from the heater to the quartz ampoule through a flexible graphite thermally conductive pad layer. This significantly reduces the temperature difference in the circumferential and vertical directions of the ampoule, resulting in more uniform heating of the indium phosphide melt. It also reduces drastic fluid convection changes caused by localized overcooling or overheating, thereby lowering the probability of dislocation defects. The carbon-carbon composite material possesses both high thermal conductivity and moderate thermal insulation. The efficient heat transfer to the quartz on the inner side and the low thermal conductivity on the outer side, which prevents heat loss through radiation, reduce the temperature difference within the furnace and stabilize the longitudinal temperature gradient. This is beneficial for achieving stable constant-diameter growth and increasing the drawing speed.

[0076] The carbon-carbon shell of this invention features a detachable design, allowing the thermocouple and fiber optic grating sensing components to be inspected, calibrated, and reused after each batch of production, significantly reducing the cost of sensing elements. The carbon-carbon shell itself employs a segmented, petal-like structure design; in the event of localized damage, only the damaged segment needs replacement, eliminating the need for complete replacement and further reducing consumable costs. Through the accompanying full-process temperature data storage and archiving and wear assessment functions, the system can quantitatively evaluate the wear status of the carbon-carbon shell and quartz ampoules, predict consumable failure cycles, achieve preventative maintenance, and avoid sudden safety accidents and production interruptions.

[0077] In another specific embodiment, the carbon fiber braid of the carbon-carbon outer shell 1 adopts a three-dimensional braided structure, which is formed by multiple layers of carbon fiber bundles interwoven in three directions, exhibiting excellent interlaminar shear strength and impact resistance. The carbon matrix is ​​densified using chemical vapor deposition, a method that allows carbon atoms to penetrate into the internal pores of the carbon fiber braid at high temperatures, forming a dense carbon matrix and ensuring the structural stability and oxidation resistance of the material under long-term working conditions.

[0078] The dual-sensor composite temperature array of this invention achieves full-coverage monitoring of the temperature field on the outer wall of the ampoule. The continuous arrangement of FBG fiber gratings along the axial and circumferential directions of the shell compensates for the shortcomings of discrete monitoring by single-point thermocouples, eliminating temperature measurement blind spots. The one-to-one pairing of fiber grating measurement points with platinum-rhodium thermocouple measurement points ensures that each region possesses a high-precision true reference temperature and the ability to continuously monitor temperature change trends. The dual-sensor real-time calibration mechanism effectively offsets the temperature drift caused by the fiber under long-term high-temperature conditions. After correction using a multi-layer thermal resistance model, the melt temperature measurement error is controlled within ±0.3 degrees Celsius, significantly improving temperature control accuracy and providing a reliable data foundation for precise and stable control of the indium phosphide crystal growth temperature gradient.

[0079] The graded thermal anomaly active explosion-proof interlocking system of this invention can accurately distinguish three different types of thermal anomaly conditions and execute targeted graded responses. Unlike existing technologies that only set a fixed over-temperature threshold for a single interlocking logic, this invention's system can identify different characteristics such as uniform drift caused by sensor aging, temperature spikes caused by localized damage, and drastic axial temperature differences caused by structural failure, and execute differentiated response strategies such as parameter compensation, first-level early warning, and second-level interlocking accordingly. This graded response method effectively avoids unnecessary shutdowns caused by misjudgments due to sensor aging, ensuring the continuity and stability of the crystal growth process. Simultaneously, it can promptly trigger explosion-proof actions when a genuine structural failure risk occurs, preventing the accident from escalating.

[0080] In practical implementation, eight sets of arrayed snap-fit ​​structures are set at the docking edges of the upper and lower petals, evenly distributed along the petal edges. The tongue 7a and groove 7b are interference-fitted to ensure that the snap-fit ​​structure does not loosen under high-temperature conditions. Carbon carbon straps 8 are set at the top and bottom of the shell, with moderate binding force, which can restrain the radial expansion of the shell without causing excessive compressive stress on the shell.

[0081] In the specific implementation of the flexible graphite thermal conductive pad, the pad is made of compressible flexible graphite rolls laid along the gap between the outer wall of the quartz ampoule and the inner wall of the carbon-carbon shell. The pad is pre-cut to a shape matching the ampoule's shape before assembly, and during installation, it is wrapped layer by layer from the bottom of the ampoule upwards, ensuring no air bubbles or wrinkles between the pad and the ampoule's outer wall. After the platinum-rhodium thermocouple probe is embedded in the designated position inside the pad, the pad is moderately compressed using flexible graphite clamps, achieving a zero-gap fit between the thermocouple probe and the ampoule's outer wall.

[0082] The fiber Bragg grating (FBG) is embedded during the weaving process of the carbon fiber braided layer of the carbon-carbon shell. The FBG is arranged along the axial direction of the carbon-carbon shell, penetrating three temperature measurement zones, and simultaneously wound at equal intervals along the circumference of the shell. Each platinum-rhodium thermocouple has three sets of FBG measurement points corresponding to its axial direction, achieving a one-to-one pairing relationship between discrete fixed-point temperature measurement and continuous temperature measurement across the entire axial and circumferential domains. The two ends of the FBG extend to the outside of the carbon-carbon shell, are protected by a high-temperature sheath, and then connected to the fiber optic demodulator.

[0083] In the first-level early warning response, the system sends a power reduction command to the heating power controller, reducing the heating power of the corresponding temperature zone by 10% and extending the temperature sampling interval of that zone to 30 seconds, continuously monitoring the abnormal evolution trend. In the second-level interlock protection, the system immediately sends a full-power stop command to the heating power controller and simultaneously sends a nitrogen charging command to the nitrogen charging system to increase the furnace chamber pressure. Subsequently, it executes a segmented slow cooling program to lower the temperature of each temperature zone, maintains the pressure for 2 hours, and then continues to slowly lower the temperature to room temperature.

[0084] In the specific implementation of the in-situ quality inspection linkage function, the in-situ quality inspection module receives melt temperature field data and global shell temperature field data provided by the dual-sensor system. By comparing the temperature gradient near the solid-liquid interface with the theoretical optimal temperature gradient, it evaluates the interface stability of crystal growth in real time. The theoretical optimal temperature gradient is determined based on the indium phosphide phase diagram and the crystal growth kinetic model. When the detected temperature gradient deviates from the set threshold by more than 15%, the in-situ quality inspection module automatically generates a power adjustment suggestion and sends it to the heating power controller for execution.

[0085] In the specific implementation of carbon-carbon shell lifespan assessment, the system calculates the number of temperature cycles, maximum operating temperature, and cumulative thermal stress load of the carbon-carbon shell during historical production cycles based on stored full-process temperature data and thermal anomaly warning records. The number of temperature cycles is calculated based on the number of cycles exceeding 800 degrees Celsius, the maximum operating temperature is the highest historical record value, and the cumulative thermal stress load is calculated using an integral method. By comparing with the preset carbon-carbon material fatigue life curve, when the predicted remaining service life is less than 500 hours, the system displays a replacement reminder on the interface. When the carbon-carbon shell reaches the preset replacement cycle or structural damage characteristics are detected, the system automatically generates a replacement reminder work order to guide maintenance personnel to replace it in a timely manner.

[0086] Specific embodiments of the present invention also include embodiments in which the carbon fiber braid of the carbon-carbon shell body adopts an orthogonal braiding structure. The orthogonal braiding structure is formed by alternating weft and woven warp carbon fiber bundles. The interlayer shear strength is slightly lower than that of the three-dimensional braiding structure, but the manufacturing cost is lower, making it suitable for applications with relatively low impact performance requirements.

[0087] In another specific embodiment, the observation aperture employs a quartz glass sealed window structure, with the quartz glass bonded to the carbon-carbon outer shell using high-temperature ceramic adhesive, capable of withstanding temperatures up to 1200 degrees Celsius without detachment. A removable protective cover is provided on the outside of the observation aperture to protect the window from contamination during non-observation periods.

[0088] The precision temperature-measuring explosion-proof shell and its temperature measurement method of this invention achieve safety protection and precise temperature control throughout the entire process of indium phosphide crystal growth by using physical explosion-proof protection of carbon-carbon composite materials, full-range temperature monitoring of dual-sensor composite temperature measurement array, high-precision temperature calculation of dual-sensor calibration and multi-layer thermal resistance temperature inversion algorithm, and intelligent graded response of graded thermal anomaly active explosion-proof interlocking system. It effectively solves the technical defects of existing technologies such as lack of explosion-proof protection for ampoules, insufficient single-point temperature measurement accuracy, and lack of early fault warning. While improving the safety of crystal growth, it significantly improves crystal quality, reduces production costs, and increases production efficiency.

[0089] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A precision temperature-measuring explosion-proof housing for indium phosphide crystal growth, characterized in that, include: The explosion-proof housing body (1) is made of carbon-carbon composite material; a flexible graphite thermal conductive pad (2) is disposed between the explosion-proof housing body (1) and the quartz ampoule (6); and a dual-sensor composite temperature measuring array (3) is integrated into the explosion-proof housing body (1); the explosion-proof housing body (1) is made of high-temperature resistant and high-strength carbon-carbon composite material, which is composed of carbon fiber braid and carbon matrix. Its overall structure is cylindrical, and the inner cavity contour is designed to match the outer surface of the quartz ampoule (6) in a contour matching manner, which can completely cover the side wall, bottom and top sealing area of ​​the quartz ampoule (6 ...; a flexible graphite thermal conductive pad (2) is disposed between the explosion-proof housing body (1) and the quartz ampoule (6); and a dual-sensor composite temperature measuring array (3) is integrated into the explosion-proof housing body (1); the explosion-proof housing body (1) is made of high-temperature resistant and high-strength carbon-carbon composite material, which is composed of carbon fiber braid and carbon matrix. Its overall structure is cylindrical, and the inner cavity contour is designed to match the outer surface of the quartz ampoule (6) in a contour matching manner, which can completely cover the side wall, bottom and top sealing area of ​​the quartz ampoule (6); the explosion-proof housing body (1) is made of high-temperature resistant and high-strength carbon-carbon composite material; the explosion-proof housing body (1) is made of high-temperature resistant The explosion-proof outer shell body (1) is divided into two independent petals. Each petal has multiple sets of array-type snap-fit ​​structures (7) at its mating edge. Adjacent petals are locked together by the snap-fit ​​structures (7) to form a closed cylindrical protective structure. The snap-fit ​​structure (7) includes a protruding tongue (7a) on the edge of one petal and a groove (7b) on the edge of the other petal. The protruding tongue (7a) and the groove (7b) are mechanically locked by an interference fit. At least two straps (8) made of carbon-carbon composite material are fitted on the outside of the explosion-proof outer shell body (1). The straps (8) are arranged around the circumference of the outer shell.

2. The precision temperature measurement explosion-proof housing according to claim 1, characterized in that, The flexible graphite thermal pad (2) is filled in the interlayer space between the explosion-proof shell body (1) and the quartz ampoule (6). It is made of compressible flexible graphite roll material and is laid along the gap between the outer wall of the quartz ampoule (6) and the inner wall of the carbon shell, so that the temperature measuring element and the outer wall of the quartz ampoule (6) can be fitted with zero gap, while providing an axial thermal channel.

3. The precision temperature measurement explosion-proof housing according to claim 1, characterized in that, The dual-sensor composite temperature measurement array (3) includes a platinum-rhodium thermocouple temperature measurement unit (4) and a high-temperature resistant fiber optic grating temperature measurement unit (5); the platinum-rhodium thermocouple temperature measurement unit (4) adopts PtRh30-PtRh6 type platinum-rhodium thermocouples, and there are no less than three in total, which correspond to the upper phosphorus source area, the middle melt area and the lower seed crystal area inside the quartz ampoule (6) respectively; the temperature measurement probe of each platinum-rhodium thermocouple is completely embedded in the flexible graphite thermal pad layer (2), so that it is in a gapless fit with the outer wall of the quartz ampoule (6); the lead wire of the platinum-rhodium thermocouple is protected by a high-temperature anti-oxidation ceramic sheath, and passes through the gap between the carbon shell and the furnace wall to the furnace external acquisition module; The high-temperature resistant fiber grating temperature measurement unit (5) adopts a high-temperature resistant FBG fiber grating. The fiber grating is arranged along the carbon-carbon shell through three temperature measurement areas and is wound at equal intervals along the circumference of the shell. The fiber grating is embedded in the carbon fiber braided layer of the carbon-carbon shell and forms an integrated structure with the carbon fiber braid. Each platinum-rhodium thermocouple measuring point is provided with 2 to 3 sets of fiber grating measuring points along the axial direction to realize a one-to-one pairing relationship between discrete fixed-point temperature measurement and continuous temperature measurement in the axial and circumferential directions.

4. The precision temperature measurement explosion-proof housing according to claim 1, characterized in that, The explosion-proof outer shell body (1) is divided into two independent petals: an upper petal (9) and a lower petal (10). Multiple sets of array-type snap-fit ​​structures (7) are respectively provided on the docking edges of the upper petal (9) and the lower petal (10). An observation opening is provided on the side wall of the upper petal (9). The window faces the furnace camera monitoring optical path and adopts a quartz glass sealed window structure to ensure that the industrial camera can observe the state of the indium phosphide melt and the entire crystal growth process inside the crucible without obstruction.

5. The precision temperature measurement explosion-proof enclosure according to any one of claims 1 to 4, characterized in that, The carbon-carbon composite material can be replaced with graphite, stainless steel, silicon carbide composite material or silicon carbide fiber reinforced silicon carbide composite material; when graphite material is used, the graphite shell is made of high-purity graphite blocks, the inner cavity contour matches the outer surface of the quartz ampoule (6), the graphite shell is divided into two independent petals along the dividing line, and the petals are mechanically connected and sealed through graphite material connectors.

6. A temperature measurement method based on a precision temperature-measuring explosion-proof enclosure according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1, Furnace loading and sensor assembly: The segmented carbon-carbon composite shell is fitted onto the outside of the quartz ampoule (6). The inside of the quartz ampoule (6) is divided into three functional areas along the axial direction: the upper phosphorus source area, the middle melt area, and the lower seed crystal area. A flexible graphite thermal pad (2) is installed in the interlayer between the carbon-carbon shell and the ampoule. The PtRh30-PtRh6 platinum-rhodium thermocouple is completely embedded in the pad to ensure that the thermocouple probe is in close contact with the outer wall of the quartz ampoule (6) without gaps. The high-temperature resistant FBG fiber grating is pre-embedded in the shell braiding layer along the axial direction of the carbon-carbon shell through the three temperature measurement areas and circumferentially wound at equal intervals. This ensures that 2 to 3 fiber grating measurement points are matched on both sides of each thermocouple measurement point, thus completing the one-to-one pairing arrangement of thermocouples and fiber grating measurement points. Step 2, power-on synchronization zero-point calibration of the sensing system: After the crystal growth furnace is closed and sealed, the industrial control computer, thermocouple acquisition module, and fiber optic demodulator are powered on and started simultaneously; the acquisition module completes the cold junction compensation baseline calibration of the thermocouples, and the fiber optic demodulator reads all the initial reflection wavelengths of the FBG gratings to establish the basic conversion relationship between wavelength and temperature at room temperature. The industrial control computer has a built-in time synchronization chip, which sets the synchronization time difference between the thermocouple and fiber optic grating signal acquisition to be less than 1ms, so that the time axis of the two temperature measurement data is completely aligned. After completing the full-channel self-inspection, eliminating abnormal sensor points with broken wires and short circuits, and confirming that the dual sensor array is all normal, proceed to the process flow. Step 3, Dual-sensor synchronous acquisition and real-time calibration during the heating stage: Start the programmed heating process of the crystal growth furnace and continuously and synchronously acquire dual-sensor data throughout the heating process; one path acquires the steady-state temperature of the thermocouples at each zone, and the other path acquires the reflection wavelength of all FBG gratings through the fiber demodulator and converts it to obtain the continuous temperature field distribution data of the carbon shell in the axial and circumferential directions; the industrial control extracts the temperature values ​​of the thermocouples and fiber optic gratings paired at the same position every 5 minutes, and uses the temperature measured by the high-precision platinum-rhodium thermocouple as the true value benchmark to automatically iterate and correct the wavelength and temperature conversion coefficient of the fiber optic grating in the corresponding area; the piecewise nonlinear interpolation algorithm is used, combined with the true value of the thermocouple at the fixed point and the continuous temperature measurement curve of the fiber optic, to reconstruct the complete two-dimensional temperature distribution data of the outer wall of the quartz ampoule (6); Step 4: Layered thermal resistance coupling inversion calculation of the true melt temperature. The reconstructed two-dimensional temperature field data of the ampoule outer wall is input into the multilayer heat conduction model built into the industrial control system. The contact thermal resistance and radiation heat transfer loss of each layer of carbon-carbon shell layer, flexible graphite thermal pad layer (2), quartz tube wall and barrier coating are calculated in layers to correct the temperature deviation caused by the small temperature measurement gap due to the thermal expansion mismatch of multilayer materials. The model is used to calculate and output the true melt temperature of three locations inside the ampoule: the phosphorus source vaporization zone, the InP melt center and the solid-liquid growth interface in real time, and the temperature control accuracy is stably controlled within ±0.3 degrees Celsius. Step 5: The industrial control system continuously compares the synchronous temperature change rates of thermocouples and fiber Bragg gratings in the same area, distinguishes three types of thermal anomalies, and performs graded handling. When a uniform and slow temperature shift is detected across the entire area, it is determined to be fiber Bragg grating sensor aging, and the system automatically starts the global parameter compensation program without interrupting the crystal growth process. When a short-term temperature jump is detected at a local grating measuring point and the paired thermocouples heat up synchronously, it is determined to be graphite pad detachment, microcracks in the ampoule PBN coating, or trace phosphorus vapor infiltration. The system outputs a first-level audible and visual explosion-proof warning and simultaneously reduces the heating power of the corresponding area. When a rapid increase in the axial temperature difference in a single temperature measuring interval is detected, it is determined to be the failure of the carbon-carbon shell elastic support or the ampoule eccentric tilt. The system triggers the second-level explosion-proof interlock protection and performs segmented slow cooling and nitrogen filling and pressure stabilization operations in the furnace cavity. Step Six, Closed-Loop Temperature Control in the Isothermal Synthesis Stage: During the isothermal synthesis of indium phosphide polycrystalline, the temperature measurement, calibration, temperature inversion, and anomaly identification processes from Steps Three to Five are continuously repeated; the corrected melt temperature and the global shell temperature field data are synchronously transmitted to the in-situ crystal quality detection module, the heating power of the multi-zone single crystal furnace is adjusted, the axial temperature gradient is dynamically optimized, and the generation of crystal defects such as impurities, component segregation, and porosity is suppressed; Step 7: Data storage and archiving of temperature measurement data throughout the cooling process: After crystal synthesis is completed, the process enters the gradient slow cooling process. The dual-sensor system continuously and synchronously collects, calibrates, and inverts temperature data until the furnace body cools down to room temperature. The industrial control system fully stores the original thermocouple data, fiber optic continuous temperature field curves, calibration and correction parameters, and thermal anomaly early warning records of the entire furnace heating, constant temperature, and cooling process. Step 8, Re-inspection and calibration of sensing components after furnace exit: Open the furnace and remove the carbon shell to check the integrity of the thermocouple and FBG fiber grating coating; perform standard temperature zone re-inspection and calibration of the sensing components, update the basic conversion parameters of the grating, and reuse undamaged components directly in the next synthesis process.

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